The present application claims priority to Application No. 102 13 154.6, filed in the Federal Republic of Germany on Mar. 23, 2002, which is expressly incorporated herein in its entirety by reference thereto.
The invention relates to an air conditioning system for a motor vehicle.
In the case of vehicles having an air conditioning system, there is the problem that when the air conditioning system is re-started after a short standing time the windows become misted up under certain environmental conditions. This is because after the air conditioning system is switched off, the surface of the evaporator is moist, and the warm environment in the engine compartment or in the environment causes the temperature of the air in the air conditioning box to rise. This increases the humidity of the air flowing into the vehicle interior where it brushes past the vehicle windows, in particular past the windscreen or front window. The same problem occurs in the case of vehicles having air conditioning systems which make use of the residual heat from the engine and/or have auxiliary heating. In moist, cool weather the windows become misted up because humidity has collected in the air conditioning box during the previous driving operation due to the air which has been taken into the cab being dried in the reheating mode, and the humidity is blown together with the air into the vehicle interior.
In the case of a conventional air conditioning system of the type mentioned at the beginning (German Published Patent Application No. 197 31 369), this increased tendency of the windows to become misted up is counteracted by the evaporator being bridged by a bypass, the bypass opening of which, which is situated upstream of the evaporator in the air flow direction, can be closed or opened by a controllable shut-off element. In addition, a second shut-off element is arranged in the air conditioning box between the evaporator and the heat exchanger, which shut-off element is able to shut off the entire flow cross-section between the evaporator and the heat exchanger. This second shut-off element is arranged downstream, as seen in the air flow direction, of the water outlet formed in the air conditioning box. The surface humidity of the evaporator is detected by a humidity or moisture sensor and if it exceeds a limit value a control unit is used to transfer the first shut-off element into its open position and the second shut-off element into its closed position, as a result of which a first partial air flow flows around the evaporator and a second air flow, which passes through the moist evaporator, flows off via the water outlet, which is formed in the air conditioning box, into the vehicle environment. While the vehicle interior continues to be supplied with heated or unheated air via the first partial air flow, the second partial air flow causes the evaporator to be dried. After this drying process, the two shut-off elements are changed over again, so that now all the air conveyed by the blower flows again through the evaporator.
In the case of air conditioning systems for motor vehicles, the evaporator, which is integrated in the air conditioning box, is connected into the refrigerant circuit of a cooling unit. If there are leakages in the refrigerant circuit, the refrigerant may be emitted. If these leakages occur within the air conditioning box, the quantities of toxic refrigerant which have been leaked are blown together with the blower air into the vehicle interior and lead in the long term to damage to the vehicle occupants"" health. In the case of a conventional air conditioning system (German Published Patent Application No. 198 50 914), in which CO2 is used as refrigerant, in order to avoid health-damaging CO2 concentrations in the blower air blown into the interior in the event of leakages at the evaporator, a CO2 sensor has been arranged behind the heat exchanger and one or more air flaps interrupting the supply of air from the ventilation system into the interior of the motor vehicle have been provided behind the heat exchanger, in the flow direction, in the ventilation system, the air flaps being controlled by a control unit as a function of the input signal of the CO2 sensor. If the CO2 sensor detects a CO2 concentration in the blower air emerging from the evaporator, the control unit transfers the air flaps into their closed position, as a result of which all of the blower air is blown to the outside via an overpressure outlet arranged between the evaporator and heat exchanger in the air conditioning box.
It is an object of the present invention to provide, in the case of an air conditioning system of the type mentioned above, the forced ejection of loaded blower air in a cost-effective and construction-space-saving manner with the same efficiency.
The above and other beneficial objects of the present invention may be achieved by providing an air conditioning system as described herein.
An air conditioning system according to an example embodiment of the present invention may provide that, by using the air control elements which are present in any case at the air outflow openings, which are connected to the vehicle interior, in order to eject the blower air via the water outlet, no further constructional elements may be required for the ejection, so that there may be neither an additional need for construction space in order to accommodate such constructional elements nor may costs arise for the production thereof. The ejection function may be implemented cost-effectively in the control unit for actuating the air control elements, which unit is present in any case in automatic air conditioning system.
Example embodiments of the air conditioning system according to the present invention together with further aspects, developments and refinements of the present invention are described below.
The present invention is described in greater detail below with reference to an exemplary embodiment illustrated in the drawing. The drawing illustrates a schematic illustration of a longitudinal section of an air conditioning system of a motor vehicle.